Bug Description

To reproduce:

1. Use the Dash to locate a URL. I used the bookmarks-lens but there are probably other ways.
2. Select the URL and Firefox will open it in a tab.
3. Close that tab.
4. Notice that dropdown menus such as the search engine selector or even the completion dropdowns on the awesome bar or the search box stop working.

This happens when running in safe mode as well.

As I said above it happens with the bookmarks-lens and with my simple python favorites-lens https://github.com/gbishop/favorites-lens but I don't think the problem is in the lens. Either lens is simply providing Unity with a URL.

I assume Unity is supplying the URL to Firefox with something akin to xdg-open. But xdg-open does not cause this problem.

I don't see any messages in the terminal nor in the error console when this is happening.

i think this should be reported in https://bugs.launchpad.net/askubuntu-lens page rather in Firefox, since Ask Ubuntu lens seems to be the problem . Please comment so , so i would report theis bug in Ask Ubuntu lens page.

I can't find the source of the youtube lens that does not cause this problem but I guess it handles the URI itself since it allows choosing the player to be used. If a lens handles the URI and (for example) using xdg-open to activate it, the bug is not present.

Following can be a different bug, but I hope that this is likely to be the same bug:
1. Open Thunderbird
2. Open account settings *from HUD* (it is needed to open it from HUD and NOT from Thunderbird overview page)
3. Try to expand some dropdown menu (e.g. "Outgoing Server (SMTP)" or "Server Settings / Connection Security").

The same proglem appears. The dropdown men does not expand. Since both Firefox and Thunderbird are Gecko-based and there are similar Ubuntu add-ons, I hope this is related.